Male infertility is a personal problem with significant social outspread as it affects the couple medically and psychosocially. The quality of human sperm and its fertilising potential have been dramatically decreased during the last several decades. World-wide scientific-investigative efforts focus on the pathophysiology and treatment of each singular disorder that contributes to male factor infertility. The role of neutrophils in the male genital tract and seminal fluid is rather complex and dynamic. Neutrophils, as the main component of leucocytes, are found in virtually every ejaculate and play a role on several levels. Small quantities of neutrophils have important beneficial effects in phagocytosis of abnormal sperm and immunosurveillance. This book discusses the role of polymorphonuclear neutrophils in relation to male infertility.